Flood defence house-tanking pilot being tested

Christchurch City Council is this week starting a pilot test of the 'house-tanking' flood defence measure outlined in the Mayoral Flood Taskforce report recommendations for flood mitigation.

Christchurch City Mayor, Lianne Dalziel, established the Mayoral Flood Taskforce, as a result of the heavy rainfall events in March and April of this year which caused flooding, asking the Taskforce to come up with short-term flood mitigation recommendations for the most flood vulnerable areas of Christchurch.

One of the flood defence measures designed to protect the most vulnerable houses is 'house-tanking'.

The 'house-tanking' process involves the application of a waterproof membrane to the exterior of a house including but not limited to:

* Waterproof sealing of the house structure
* Installation of non-return valves to sewer pipes on the property
* Sealing pipe and cable inlets
* Flood door barriers
* Air brick/ventilation covers
* Installation of a submersible pump beneath the floor (this option may not be used in the pilot)
John Mackie, Unit Manager Transport and Greenspace says, "All flood mitigation recommendations from the Taskforce are being carefully looked at to ensure the protection for our residents who are most at risk to flooding.

"House-tanking is one of these recommendations, so a suitable red zone property was selected to pilot the technique. The house will need to be flooded similar to the conditions experienced in March and April this year, so bunding apparatus will be set up and encircle the house. This will then be filled with water, replicating above floor level flooding. This will give us a good understanding of the house-tanking performs under flood conditions.

"This pilot allows us to make any necessary changes to improve the protection measures, thereby giving assurance to residents who will have this flood defence measure put in place for their house," Mr Mackie says.

Timeline for the 'house-tanking' pilot taking place at 37 Retreat Rd, Avonside:

Thursday 10 July 2014:
* Application of a waterproof membrane to exterior of the house and foundation.
* Clear vegetation from around house for installation of bund structures.
* Installation of water-bunding systems around the house begins.
* Install the scaffolding bridge for access to the house during the pilot.

John Mackie, Unit Manager Transport and Greenspace will be on-site from 12pm-1pm to talk about the process.

Friday 11 July 2014:
* Finish bund set-up and fill with water.
* Monitor the water level and water ingress into the house through its walls and floor.

John Mackie, Unit Manager for Transport and Greenspace will again be on-site from 2.30pm-3.30pm to talk about the process.

Saturday/Sunday 12/13 July 2014:
* Monitor the water level and water ingress into the house through its walls and floor.

Monday 14 July 2014:
* John Mackie will lead a guided walk through taking a closer look at the 'house-tanking' flood defence measure and the findings from the pilot test.

John Mackie, Unit Manager for Transport will again be on-site between 1pm-2pm to talk about the process.

Health and Safety: Please note personal protective equipment (PPE) must be worn.

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